a merry go round rotates from rest with constant angular acceleration `α` . Ratio of time to rotate first 2 revolutions & next 2 revolutions is
1) 1:1
2) (√2+1):1
3) √2:1
4) 1:√2
Answers
Hey Dear,
◆ Answer - (2)
t1/t3 = √2+1
◆ Explanation -
Given that merry go round starts from rest. So ω0 = 0 rad/s.
For first two revolutions, θ = 2×2π rad
θ = ω.t1 + 1/2 α.t1^2
2×2π = 0×t1 + 1/2 × α × t1^2
t1^2 = 8π/α
t1 = √(8π/α)
For first four revolutions, θ = 4×2π rad
θ = ω.t2 + 1/2 α.t2^2
4×2π = 0×t2 + 1/2 × α × t2^2
t2^2 = 16π/α
t2 = √(16π/α)
Time taken for 3rd and 4th revolution is -
t3 = t2 - t1
t3 = √(16π/α) - √(8π/α)
t3 = (√2-1) √(8π/α)
Now, ratio of time to rotate first 2 revolutions and next 2 revolutions is -
t1/t3 = √(8π/α) / [(√2-1)√(8π/α)]
t1/t3 = 1/(√2-1) × (√2+1)/(√2+1)
t1/t3 = √2+1
Therefore, ratio of time to rotate first 2 revolutions & next 2 revolutions is √2+1.
Thanks dear...
Answer:
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Explanation:
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